Well for a hatchie coastal I would go with a small storage box with lid (& air-holes) or even do what we did with 'Zar (our 11 month old Diamond x Carpet) for a while, keep him in a 40cm x 20cm x 10cm (Width, Depth & Height) tuppawear container with a lid on, air holes (lots of those) and a heat mat under 1/4th on the container. All you need in there with him is a little hide (light-globe box is ideal), a small water dish (a lid perhaps?) & some paper-towel/newspaper on the bottom. All up cost of the second suggested method would be about $30 + whatever the heat-mat (&/or thermostat) costs.
Hope that helps somewhat.
Kath